> Thanks! Did you measure the quality of the built index somehow? The > ordering shouldn't make any difference to the build speed, but it > affects the shape of the resulting index and the speed of queries > against it.
Again I've tried random select tests near axes and haven't noticed any performance difference between ordinary gist build and z-ordered one. The same is for selects far from axes. Theoretically, there may be a possible slowdown for particular points inside the MBR which crosses the axis but I haven't tried to dig so deep and haven't tested performance as a function of coordinate.
So I feel this patch is not about select speed optimization.